Solid-state imaging device and manufacturing method of the same, and electronic apparatus

ABSTRACT

The present disclosure relates to a solid-state imaging device and a manufacturing method of the same, and an electronic apparatus, capable of more reliably suppressing occurrence of color mixing. 
     A trench is formed between PDs so as to be opened to a light receiving surface side of a semiconductor substrate on which a plurality of the PDs, each of which receives light to generate charges, are formed, an insulating film is embedded in the trench and the insulating film is laminated on a back surface side of the semiconductor substrate. Then, a light shielding portion is formed so as to be laminated on the insulating film and to have a convex shape protruding to the semiconductor substrate at a location corresponding to the trench. The present technology can be applied to a back surface irradiation type CMOS solid-state imaging device.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/720,410, filed May 22, 2015, which is a continuation of U.S. patentapplication Ser. No. 14/372,413, filed Jul. 15, 2014, now U.S. Pat. No.9,105,539, which is a national stage application under 35 U.S.C. 371 andclaims the benefit of PCT Application No. PCT/JP2013/050406, having aninternational filing date of Jan. 11, 2013, which designated the UnitedStates, which claims the benefit of Japanese Patent Application No.2012-011125, filed Jan. 23, 2012, the entire disclosures of which arehereby incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a solid-state imaging device and amanufacturing method of the same, and an electronic apparatus, and inparticular, to a solid-state imaging device and a manufacturing methodof the same, and an electronic apparatus, capable of more reliablysuppressing occurrence of color mixing.

BACKGROUND ART

In general, in a Complementary Metal Oxide Semiconductor (CMOS) typesolid-state imaging device, a unit pixel is formed with a photo diodewhich is a light receiving unit and a plurality of transistors, and aplurality of the pixels are arranged two-dimensionally. In the CMOS typesolid-state imaging device, respective electrodes of the transistors areconnected to a multilayer wiring, and signal charges generated in thephoto diode are read as a signal current by desired voltage pulses beingapplied to the electrodes of the transistors through respective wirings.

In addition, in a Charge Coupled Device (CCD) type solid-state imagingdevice, the signal charges generated in the photo diode pass through acharge transfer unit (a vertical CCD and a horizontal CCD) configuredwith CCDs and are supplied to a charge detection unit.

Further, in recent years, a back surface irradiation type imaging devicehas been put into practical use in which light is applied to a backsurface side which is the side opposite to a front surface on whichwiring layers are laminated on a device substrate in which the photodiode and the transistors are formed. In the back surface irradiationtype imaging device, charges by photoelectric conversion occur mostfrequently in the back surface side of the device substrate. Therefore,if color mixing occurs due to leakage of electrons generated byphotoelectric conversion in a vicinity of the back surface of the devicesubstrate to adjacent pixels, a signal characteristic deteriorates, andthus suppressing the occurrence of such color mixing is important.

However, when the formation of impurities for performing elementisolation between the photodiodes is performed by ion implantation fromthe front surface side of the device substrate and annealing, a methodby high-energy implantation disclosed in PTL 1 is employed.

However, in a deep position of the back surface side far from the frontsurface of the device substrate to which the ion implantation isperformed, ions diffuse to extend in a transverse direction.Accordingly, in a fine pixel, since an electric field in the transversedirection in the vicinity of the back surface of the device substrate isweak, it is difficult to suppress the color mixing due to the leakage ofelectrons generated by the photoelectric conversion to adjacent pixels.

Therefore, as disclosed in PTL 2, the present applicant has proposed amethod which physically separates pixels by forming a trench on the backsurface of the device substrate and suppresses the leakage of charges toadjacent pixels by embedding metal in the trench portion.

CITATION LIST Patent Literature

PTL 1: Japanese Unexamined Patent Application Publication No.2003-318122

PTL 2: Japanese Unexamined Patent Application Publication No. 2011-3860

SUMMARY OF INVENTION Technical Problem

Meanwhile, in a structure disclosed in PTL 2, it is effective to form adeep trench as a method for suppressing incidence of light in an obliquedirection or suppressing occurrence of shading. However, when a lightshielding metal film is embedded in the deep trench which is formed, aninterference characteristic deteriorates due to formation of the metalfilm such that noise and white spots due to a dark current occur, whichresults in a concern that an image quality deteriorates. Therefore,avoiding the deterioration in the image quality and suppressing theoccurrence of the color mixing are required.

The present disclosure has been made in view of such circumstances, andis intended to be able to more reliably suppress occurrence of colormixing.

Solution to Problem

A solid-state imaging device according to an aspect of the presentdisclosure includes a semiconductor substrate on which a plurality ofphotoelectric conversion units, each of which receives light to generatecharges, are formed; a recessed portion that is formed between thephotoelectric conversion units so as to be opened to a light receivingsurface side of the semiconductor substrate; an insulating film which isembedded in the recessed portion and laminated on the back surface sideof the semiconductor substrate; and a light shielding portion that islaminated on the insulating film and is formed into a convex shapeprotruding to the semiconductor substrate at a location corresponding tothe recessed portion.

A manufacturing method according to another aspect of the presentdisclosure includes the steps of forming a recessed portion betweenphotoelectric conversion units so as to be opened to a light receivingsurface side of a semiconductor substrate on which a plurality of thephotoelectric conversion units, each of which receives light to generatecharges, are formed; embedding an insulating film in the recessedportion and laminating the insulating film on a back surface side of thesemiconductor substrate; and laminating a light shielding portion on theinsulating film and forming the light shielding portion into a convexshape protruding to the semiconductor substrate at a locationcorresponding to the recessed portion.

An electronic apparatus according to still another aspect of the presentdisclosure includes a solid-state imaging device including asemiconductor substrate on which a plurality of photoelectric conversionunits, each of which receives light to generate charges, are formed; arecessed portion that is formed between the photoelectric conversionunits so as to be opened to a light receiving surface side of thesemiconductor substrate; an insulating film which is embedded in therecessed portion and laminated on the back surface side of thesemiconductor substrate; and a light shielding portion that is laminatedon the insulating film and is formed into a convex shape protruding tothe semiconductor substrate at a location corresponding to the recessedportion.

According to still another aspect of the present disclosure, a recessedportion is formed between photoelectric conversion units so as to beopened to a light receiving surface side of a semiconductor substrate onwhich a plurality of the photoelectric conversion units, each of whichreceives light to generate charges, are formed, an insulating film isembedded in the recessed portion and the insulating film is laminated ona back surface side of the semiconductor substrate. Then, a lightshielding portion is laminated on the insulating film and is formed intoa convex shape protruding to the semiconductor substrate at a locationcorresponding to the recessed portion.

Advantageous Effects of Invention

According to the aspects of the present disclosure, it is possible tomore reliably suppress occurrence of color mixing.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a configuration example of animaging device to which an embodiment of the present technology isapplied.

FIG. 2 is a diagram illustrating a cross-sectional configuration exampleof the imaging device.

FIG. 3 is a diagram illustrating a first process of manufacturing theimaging device.

FIG. 4 is a diagram illustrating a second process of manufacturing theimaging device.

FIG. 5 is a diagram illustrating a third process of manufacturing theimaging device.

FIG. 6 is a diagram illustrating a fourth process of manufacturing theimaging device.

FIG. 7 is a diagram illustrating a fifth process of manufacturing theimaging device.

FIG. 8 is a diagram illustrating a sixth process of manufacturing theimaging device.

FIG. 9 is a diagram illustrating a seventh process of manufacturing theimaging device.

FIG. 10 is a diagram illustrating an eighth process of manufacturing theimaging device.

FIG. 11 is a diagram illustrating a ninth process of manufacturing theimaging device.

FIG. 12 is a diagram illustrating a first modified example of theimaging device.

FIG. 13 is a diagram illustrating a second modified example of theimaging device.

FIG. 14 is a block diagram illustrating a configuration example of animaging apparatus mounted on an electronic apparatus.

DESCRIPTION OF EMBODIMENTS

Hereinafter, specific embodiments to which the present technology isapplied will be described in detail with reference to drawings.

FIG. 1 is a block diagram illustrating a configuration example of animaging device to which an embodiment of the present technology isapplied.

As illustrated in FIG. 1, an imaging device 11 is a CMOS-typesolid-state imaging device, and is configured to include a pixel arrayunit 12, a vertical driving unit 13, a column processing unit 14, ahorizontal driving unit 15, an output unit 16, and a driving controlunit 17.

The pixel array unit 12 includes a plurality of pixels 21 which arearranged in an array shape, is connected to the vertical driving unit 13through a plurality of horizontal signal lines 22 corresponding to thenumber of rows of the pixels 21, and is connected to the columnprocessing unit 14 through a plurality of vertical signal lines 23corresponding to the number of columns of the pixels 21. In other words,the plurality of pixels 21 included in the pixel array unit 12 arerespectively disposed at points in which the horizontal signal lines 22and the vertical signal lines 23 intersect.

The vertical driving unit 13 sequentially supplies drive signals(transfer signals, selection signals, reset signals, or the like) fordriving respective pixels 21 to respective rows of the plurality ofpixels 21 included in the pixel array unit 12 through the horizontalsignal line 22.

The column processing unit 14 extracts the signal levels of the pixelsignals by performing a Correlated Double Sampling (CDS) process on thepixel signals which are output from respective pixels 21 through thevertical signal line 23 and acquires pixel data corresponding to theamount of received light of the pixels 21.

The horizontal driving unit 15 sequentially supplies the columnprocessing unit 14 with drive signals for outputting pixel data which isacquired from respective pixels 21 from the column processing unit 14 innumber order, for each column of the plurality of pixels 21 included inthe pixel array unit 12.

The pixel data is supplied from the column processing unit 14 to theoutput unit 16 at a timing corresponding to the drive signal of thehorizontal driving unit 15, and the output unit 16 amplifies, forexample, the pixel data and outputs the amplified pixel data to an imageprocessing circuit in the subsequent stage.

The driving control unit 17 controls the driving of each block in theimaging device 11. For example, the driving control unit 17 generates aclock signal according to the driving period of each block and suppliesthe clock signal to each block.

Further, as illustrated on a right upper part of FIG. 1, the pixel 21 isconfigured to include a PD 24, a transfer transistor 25, an FD 26, anamplification transistor 27, a selection transistor 28, and a resettransistor 29.

The PD 24 is a photoelectric conversion unit, which receives lightapplied to the pixel 21 and generates charges corresponding to theamount of the light to accumulate the generated charges.

The transfer transistor 25 is driven according to a transfer signalsupplied from the vertical driving unit 13 through the horizontal signalline 22, and when the transfer transistor 25 is turned ON, the chargesaccumulated in the PD 24 are transferred to the FD 26.

The FD 26 is a floating diffusion region having a predeterminedcapacity, which is formed at a connection portion between the transfertransistor 25 and a gate electrode of the amplification transistor 27,and accumulates charges transferred from the PD 24 through the transfertransistor 25.

The amplification transistor 27 is connected to a power potential VDD,and outputs a pixel signal of a level corresponding to chargesaccumulated in the FD 26 to the vertical signal line 23 through theselection transistor 28.

The selection transistor 28 is driven according to a selection signalsupplied from the vertical driving unit 13 through the horizontal signalline 22, and when the selection transistor 28 is turned ON, the pixelsignal output from the amplification transistor 27 is in a state capableof being output to the vertical signal line 23.

The reset transistor 29 is driven according to a reset signal suppliedfrom the vertical driving unit 13 through the horizontal signal line 22,and when the reset transistor 29 is turned ON, the charges accumulatedin the FD 26 are discharged to the power potential VDD and the FD 26 isreset.

In addition, in the imaging device 11 illustrated in FIG. 1, although acircuit configuration is adopted in which the selection of the pixel 21which outputs the pixel signal is performed by the selection transistor28, a circuit structure (so-called, three-transistor structure) in whichthe selection transistor 28 is omitted can be employed. Further, theimaging device 11 can adopt a pixel sharing structure in which the PDs24 and the transfer transistors 25 of a predetermined number share theFD 26, the amplification transistor 27, the selection transistor 28, andthe reset transistor 29.

FIG. 2 is a diagram illustrating a cross-sectional configuration exampleof the imaging device 11. Further, FIG. 2 illustrates a cross-sectionalview of a vicinity of three pixels 21-1 to 21-3 included in the imagingdevice 11.

The imaging device 11 performs imaging by light applied from the upperpart of the FIG. 2, and is configured with an on-chip lens 31, a colorfilter 32, a light receiving layer 33, a multilayer wiring layer 34, anda supporting substrate 35, which are laminated in order from the upperpart. In other words, the imaging device 11 is a so-called back surfaceirradiation type CMOS solid-state imaging device in which light isapplied from a back surface side which is opposite to a front surface,assuming the front surface is a surface on which the multilayer wiringlayer 34 is formed on the light receiving layer 33.

The on-chip lens 31 is formed of a small lens disposed for each of thepixels 21-1 to 21-3, and condenses light applied to the imaging device11 to each of the PDs 24-1 to 24-3 of the pixels 21-1 to 21-3.

The color filter 32 is formed by disposing a filter which transmitslight of a predetermined color in each of the pixels 21-1 to 21-3, andcauses the light of corresponding color, among light beams applied tothe imaging device 11, to be applied to the PDs 24-1 to 24-3 of pixels21-1 to 21-3.

In the light receiving layer 33, for example, the PDs 24-1 to 24-3, thetransfer transistors 25-1 to 25-3, and the FDs 26-1 to 26-3 are formedfor each of the pixels 21-1 to 21-3, on a semiconductor substrate 41made from a silicon wafer. Then, in the light receiving layer 33,trenches 42-1 to 42-3 are formed so as to separate the pixels 21-1 to21-3, and a fixed charge film 43, an insulating film 44, and aplanarizing film 45 are laminated. Further, in the light receiving layer33, light shielding portions 46-1 to 46-3 are formed between theinsulating film 44 and the planarizing film 45.

The PDs 24-1 to 24-3 are configured to be formed in such a manner that aP-type region and an N-type region are joined in the inside of thesemiconductor substrate 41, and receive light which is condensed by theon-chip lens 31 and passed through the color filter 32 so as to generatecharges corresponding to the amount of the light.

The transfer transistors 25-1 to 25-3 are respectively configured tohave gate electrodes 48-1 to 48-3 which are laminated on the frontsurface (a surface facing the lower part of FIG. 2) of the semiconductorsubstrate 41 through the insulating films 47-1 to 47-3. The transfertransistors 25-1 to 25-3 are respectively disposed between the PDs 24-1to 24-3 and the FDs 26-1 to 26-3. Then, if the transfer signals suppliedto the gate electrodes 48-1 to 48-3 are at a high level, the chargesaccumulated in the PDs 24-1 to 24-3 are transferred to the FDs 26-1 to26-3 through the corresponding transfer transistors 25-1 to 25-3.

The FDs 26-1 to 26-3 are dense N-type regions which are formed so as tobe in contact with the front surface of the semiconductor substrate 41,and accumulates the charges transferred from the corresponding PDs 24-1to 24-3.

The trenches 42-1 to 42-3 are recessed portions which are formed betweenthe PDs 24-1 to 24-3 so as to be opened in the back surface (a surfacefacing the upper part of FIG. 2) which is a light receiving surface ofthe semiconductor substrate 41.

The fixed charge film 43 is a film having negative fixed charges whichis provided in order not to deplete a silicon layer near the boundarysurface in the back surface of the semiconductor substrate 41, and isformed along the shape of the back surface of the semiconductorsubstrate 41.

The insulating film 44 has an insulating property, and fills the insideof the trenches 42-1 to 42-3 while being laminated on the back surfaceof the semiconductor substrate 41.

The planarizing film 45 is a film for planarizing a surface in which thelight shielding portions 46-1 to 46-3 are formed in order to laminatethe color filter 32 on the light receiving layer 33.

The light shielding portions 46-1 to 46-3 shield the light incident onthe pixels 21-1 to 21-3 in an oblique direction, thereby preventingcolor mixing between adjacent pixels 21-1 to 21-3 due to the lightincident in the oblique direction. For example, the light shieldingportion 46-1 shields the light directing the adjacent pixel 21-1 fromthe pixel 21-2 in the oblique direction, and prevents the light fromtransmitting through the color filter 32 of the pixel 21-2 and enteringthe PD 24-1 of the pixel 21-1.

Further, the light shielding portions 46-1 to 46-3 are formed into aconvex shape protruding to the semiconductor substrate 41 side in orderto improve the light shielding property. Further, the light shieldingportions 46-1 to 46-3 are formed into lengths sufficient for preventingthe leading ends from entering the trenches 42-1 to 42-3. In otherwords, the leading ends of the light shielding portions 46-1 to 46-3protruding to the semiconductor substrate 41 side are formed so as tonot enter the trenches 42-1 to 42-3 formed on the semiconductorsubstrate 41.

The multilayer wiring layer 34 is configured in such a manner that aplurality of layers of wirings constituting, for example, the horizontalsignal line 22 and the vertical signal line 23 of FIG. 1 are laminatedbetween the inter-layer insulating films 51, and in the configurationexample of FIG. 2, three layers of wirings 52-1 to 52-3 are laminated.Further, through electrodes 53-1 and 53-2 which connect wirings 52-1 to52-3 to each other and through electrodes 54-1 to 54-3 which connect theFDs 26-1 to 26-3 and the wiring 42-1 are formed on the multilayer wiringlayer 34.

The supporting substrate 35 is a base for ensuring the strength of thelight receiving layer 33 formed as a thin film and supporting the lightreceiving layer 33.

The imaging device 11 is configured in this manner and the lightshielding portion 46 shields light incident in an oblique direction,thereby preventing the light from leaking to other adjacent pixels 21and suppressing the occurrence of color mixing. For example, in aconfiguration in which the light shielding portion is formed in a planemanner, in an insulating film portion of an upper layer, it is assumedthat obtaining a sufficient light shielding property is difficult andsuppression of the color mixing is insufficient. In contrast, in theimaging device 11, the light shielding portion 46 is formed into aconvex shape protruding to the semiconductor substrate 41 side, suchthat even in the configuration in which the light shielding portion isformed in a plane manner, it is possible to improve light shieldingproperty with respect to the light incident in the oblique direction.Thus, the imaging device 11 can more reliably suppress the occurrence ofcolor mixing.

Further, for example, in the configuration in which the light shieldingportion 46 extends to the inside of the trench 42, there is a concernthat a dark current and white spots are exacerbated due to deteriorationin interface characteristics. In contrast, in the imaging device 11,since the light shielding portions 46-1 to 46-3 are formed so as to notenter the trenches 42-1 to 42-3, it is possible to make improvements forthe dark current and white spots, and to avoid degradation in imagequality.

Further, since the imaging device 11 performs the element isolationbetween pixels 21 by filling the trench 42 with the insulating film 44,for example, even in a configuration in which the element isolation isperformed by ion implantation and annealing, it is possible to morereliably perform the element isolation. Thus, it is possible to reliablyprevent color mixing even if a pixel isolation region with a narrowwidth is formed in response to miniaturization of the imaging device 11.Further, it is possible to increase a capacity of the PD 24 inparticular, and to increase the capacity of the PD 24 in a blue regionin the vicinity of a light receiving surface in the imaging device 11,thereby increasing a saturation signal amount and improving a dynamicrange.

Next, a manufacturing method of the imaging device 11 will be describedwith reference to FIGS. 3 to 11.

In a first process, as illustrated in FIG. 3, PDs 24-1 to 24-3 and FDs26-1 to 26-3 are formed by ion implantation performed on the frontsurface side (upper part of FIG. 3) of the semiconductor substrate 41.Thereafter, transfer transistors 25-1 to 25-3 are formed by laminatingthe insulating films 47-1 to 47-3 and the gate electrodes 48-1 to 48-3on the front surface of the semiconductor substrate 41. In addition,without being illustrated, the other transistors, that is, theamplification transistor 27, the selection transistor 28, and the resettransistor 29 in FIG. 1 are also formed in the same manner as in thetransfer transistor 25.

Then, after an inter-layer insulating film 51 is laminated, contactholes are formed on the inter-layer insulating film 51, and throughelectrodes 54-1 to 54-3 are formed at the contact holes so as to beconnected to respective FDs 26-1 to 26-3. In addition, in the samemanner, a through electrode (not illustrated) for supplying a transfersignal is formed so as to be connected to the gate electrodes 48-1 to48-3.

In a second process, as illustrated in FIG. 4, the multilayer wiringlayer 34 is formed by the wirings 52-1 to 52-3 and the throughelectrodes 53-1 and 53-2 are formed so as to be respectively insulatedby the inter-layer insulating film 51.

In other words, the multilayer wiring layer 34 is formed through thefollowing manner: after the wiring 52-1 is formed on the inter-layerinsulating film 51 laminated in the first process, the inter-layerinsulating film 51 is laminated and the through electrode 53-1 is formedso as to form the wiring 52-2 on the inter-layer insulating film 51, andfurther, the inter-layer insulating film 51 is laminated and the throughelectrode 53-2 is formed so as to form the wiring 52-3 on theinter-layer insulating film 51, and then the inter-layer insulating film51 is further laminated.

In a third process, as illustrated in FIG. 5, the supporting substrate35 is bonded to the multilayer wiring layer 34 from the top of themultilayer wiring layer 34.

In a fourth process, as illustrated in FIG. 6, the back surface side ofthe semiconductor substrate 41 is inverted to face upward, and the backsurface side of the semiconductor substrate 41 is scraped off with highaccuracy until the semiconductor substrate 41 has a desired filmthickness; for example, the bottom of a vertical type transistor whichis not shown is exposed. For example, a Chemical Mechanical Polishing(CMP) method, a dry etching, a wet etching, or the like can be used forthe process, and a combination of these methods can also be used.

In a fifth process, as illustrated in FIG. 7, the trenches 42-1 to 42-3are formed in an element isolation region between respective PDs 24-1 to24-3 at a predetermined depth, for example, at a depth of about 2 μmfrom the back surface of the semiconductor substrate 41. For example,the dry etching can be used in forming the trenches 42-1 to 42-3.

In a sixth process, as illustrated in FIG. 8, a fixed charge film 43 isformed along the shape of the back surface of the semiconductorsubstrate 41. In other words, the fixed charge film 43 is formed notonly on the back surface of the semiconductor substrate 41 but also onthe side surfaces and the bottom surfaces of the trenches 42-1 to 42-3formed in the semiconductor substrate 41. Further, for example, a HfO2(hafnium oxide) film formed by an Atomic Layer Deposition (ALD) methodcan be used as the fixed charge film 43.

In seventh and eighth processes, as illustrated in FIG. 9 and FIG. 10,an insulating film 44 is formed so as to be embedded in the trenches42-1 to 42-3. Further, a film forming method of forming the concaveportions 49-1 to 49-3 in which the back surface of the insulating film44 is concave as a V-shape, depending on the locations of trenches 42-1to 42-3, is adopted in forming the insulating film 44. For example, theconcave portions 49-1 to 49-3 are formed by forming the insulating film44 as a two-layer structure (laminated structure) in which after an SiO2film is formed by the ALD method, an oxide film is formed by a HighDensity Plasma (HDP)

In other words, in the seventh process, as illustrated in FIG. 9, aninsulating film 44-1 is formed by the ALD method, and in the eighthprocess, as illustrated in FIG. 10, an insulating film 44-2 is formed bythe HDP. Since the film formation and the sputtering are simultaneouslyperformed in the film formation by the HDP, as illustrated in FIG. 10,the concave portions 49-1 to 49-3 of substantially V-shape linearlycutting into shoulder portions of the trenches 42-1 to 42-3 are formed.

In a ninth process, as illustrated in FIG. 11, light shielding portions46-1 to 46-3 are formed for the insulating film 44, depending onlocations at which the trenches 42-1 to 42-3 are formed. In other words,as illustrated in FIG. 10, the concave portions 49-1 to 49-3 are formedon the insulating film 44, depending on locations at which the trenches42-1 to 42-3 are formed, and the light shielding portions 46-1 to 46-3are formed along the shape of the front surface of the concave portions49-1 to 49-3. Accordingly, the light shielding portions 46-1 to 46-3 isformed so as to have a convex shape protruding to the semiconductorsubstrate 41 in such a manner that the cross sectional shape is asubstantially V-shape.

For example, the light shielding portions 46-1 to 46-3 are formed byperforming a process of removing parts other than the locations whichare required for a light shielding structure after metal films formingthe light shielding portions 46-1 to 46-3 are formed by a sputteringmethod or a CVD method. Further, a laminated film of titanium (Ti) andtungsten (W), or a laminated film of titanium nitride (TiN) and tungsten(W) can be used as the light shielding portions 46-1 to 46-3. Further,the insulating film 44 is formed so as to fill the inside of the trench42, which prevents the leading end of the light shielding portion 46from entering the trench 42.

Thereafter, as illustrated in FIG. 2, the light receiving layer 33 isformed by laminating the planarizing film 45, and the imaging device 11is manufactured by laminating the color filter 32 and the on-chip lens31 on the light receiving layer 33.

As described above, in the imaging device 11, the trench 42 is formed soas to perform element isolation between the PDs 24, thereby allowing theinsulating film 44 to be formed in such a manner that the concaveportion 49 is formed between the PDs 24. Accordingly, it is possible toeasily form the light shielding portion 46 having a convex shapeprotruding to the semiconductor substrate 41 side, using the concaveportion 49 of the insulating film 44. Thus, it is possible tomanufacture the imaging device 11 capable of reliably suppressing theoccurrence of color mixing.

In addition, the cross sectional shapes of the light shielding portions46-1 to 46-3 may have shapes other than the substantially V-shape asillustrated in FIG. 2. For example, it is possible to vary the shapes ofthe concave portions 49-1 to 49-3 of the insulating film 44 by a filmforming method, and to make the cross-sectional shapes of the lightshielding portions 46-1 to 46-3 have shapes other than the substantiallyV-shape, depending on the shapes of the concave portions 49-1 to 49-3.

A first modified example of the imaging device 11 will be described withreference to FIG. 12. In addition, in an imaging device 11′ illustratedin FIG. 12, the illustration of the on-chip lens 31, the color filter32, the multilayer wiring layer 34, and the supporting substrate 35 isomitted.

For example, as illustrated in FIG. 9, in the seventh process, after theinsulating film 44-1 is formed by the ALD method, as illustrated in theupper part of FIG. 12, in the eighth process, an insulating film 44′ isformed by forming an insulating film 44-2′ by a Plasma Tetra EthylOxysilane (P-TEOS). In the film formation by the P-TEOS, the concaveportions 49-1 to 49-3 are formed into a shape in which the front surfaceis concave in a curved shape so as to have a steep slope to the center.

Accordingly, thereafter, in the ninth process, when light shieldingportions 46 a-1 to 46 a-3 are formed along the front surface shapes ofthe concave portions 49-1 to 49-3, as illustrated in the lower part ofFIG. 12, the cross-sectional shape is formed in such a manner that theupper and lower surfaces have a convex shape protruding to thesemiconductor substrate 41 in a curved shape.

In this manner, it is possible to form the light shielding portions 46-1to 46-3 in a desired shape by the film formation method of theinsulating film 44.

In addition, the structure of the insulating film 44 is not limited to aconfiguration example (refer to FIG. 9 and FIG. 10) in which theinsulating film 44-2 formed by the HDP is laminated on the insulatingfilm 44-1 formed by the ALD method and a configuration example (refer toFIG. 12) in which the insulating film 44-2′ formed by the P-TEOS islaminated on the insulating film 44-1 formed by the ALD method. In otherwords, if light shielding portion 46 can be formed into a convex shapeprotruding to the semiconductor substrate 41, it is possible to adoptstructures other than the configuration examples as the structure of theinsulating film 44. For example, as the structure of the insulating film44, a configuration in which an insulating film formed by the ALD methodis laminated on the insulating film formed by the P-TEOS, aconfiguration of a single film formed by the P-TEOS, or a configurationof a single film formed by the ALD method may be adopted.

Further, the light shielding portions 46-1 to 46-3 may be formed, forexample, in such a manner that after the insulating film 44 is formed tobe planarized, recessed portions are formed depending on locations atwhich the trenches 42-1 to 42-3 are formed, and the insulating film isembedded in the recessed portion.

In other words, FIG. 13 illustrates a second modified example of theimaging device 11. In addition, in an imaging device 11″ illustrated inFIG. 13, the illustration of the on-chip lens 31, the color filter 32,the multilayer wiring layer 34, and the supporting substrate 35 isomitted.

As illustrated in FIG. 13, light shielding portions 46 b-1 to 46 b-3 areformed into cross-sectional shapes of a T-shape, depending on therecessed portions formed in the insulating film 44.

In this manner, the light shielding portions 46-1 to 46-3 can be formedinto any cross-sectional shape of a convex shape protruding to thesemiconductor substrate 41, so as to obtain a better light shieldingproperty.

Further, the imaging device 11 described above can be applied to variouselectronic apparatuses including imaging systems such as digital stillcameras and digital video cameras, mobile phones with an imagingfunction, or other apparatuses with an imaging function.

FIG. 14 is a block diagram illustrating a configuration example of animaging apparatus mounted on an electronic apparatus.

As illustrated in FIG. 14, an imaging apparatus 101 is configured toinclude an optical system 102, an imaging device 103, a signalprocessing circuit 104, a monitor 105, and a memory 106, and is capableof capturing still images and moving images.

The optical system 102 is configured to include one or a plurality oflenses, and guides image light (incident light) from an object to theimaging device 103 so as to form an image on a light receiving surface(sensor unit) of the imaging device 103.

As the imaging device 103, the imaging devices 11 of the configurationexamples and the modified examples described above are applied.Electrons are accumulated in the imaging device 103 for a fixed period,according to an image formed on the light receiving surface through theoptical system 102. Thus, signals according to the electrons accumulatedin the imaging device 103 are supplied to the signal processing circuit104.

The signal processing circuit 104 performs various signal processes onthe signal charges which are output from the imaging device 103. Theimage (image data) obtained by the signal processing circuit 104performing the signal processes is supplied to and displayed on themonitor 105, or is supplied to and stored (recorded) in the memory 106.

In the imaging apparatus 101 configured in this manner, it is possibleto obtain a good quality image in which the occurrence of color mixingis suppressed, by applying the imaging device 11 of the configurationexamples or the modified examples as described above as the imagingdevice 103.

In addition, the imaging device 11 can also be applied to a frontsurface irradiation type CMOS solid-state imaging device in whichincidence light is applied from a front surface side on which themultilayer wiring layer 34 is formed on the light receiving layer 33,and the light shielding portion 46 is formed between the light receivinglayer 33 and the multilayer wiring layer 34.

In addition, the present technology may have the followingconfigurations.

(1)

A solid-state imaging device including:

a semiconductor substrate on which a plurality of photoelectricconversion units, each of which receives light to generate charges, areformed;

a recessed portion that is formed between the photoelectric conversionunits so as to be opened to a light receiving surface side of thesemiconductor substrate;

an insulating film which is embedded in the recessed portion andlaminated on the back surface side of the semiconductor substrate; and

a light shielding portion that is laminated on the insulating film andis formed into a convex shape protruding to the semiconductor substrateat a location corresponding to the recessed portion.

(2)

The solid-state imaging device according to (1),

in which the light shielding portion is formed into a length sufficientto prevent a leading end on the semiconductor substrate side fromentering the recessed portion.

(3)

The solid-state imaging device according to (1) or (2),

in which when the insulating film is formed, a concave portion in whicha surface of the insulating film is concave is formed, depending on alocation of the recessed portion.

(4)

The solid-state imaging device according to any one of (1) to (3),

in which the insulating film is configured as a laminated structure inwhich a plurality of layers are laminated.

(5)

The solid-state imaging device according to any one of (1) to (4),

in which with respect to the light receiving surface of thesemiconductor substrate in which the recessed portion is formed, after afixed charge film having negative fixed charges is formed, theinsulating film is formed.

(6)

The solid-state imaging device according to any one of (1) to (5),

in which light is applied to a back surface which is a side opposite toa front surface on which a wiring layer is laminated on thesemiconductor substrate.

In addition, the present embodiments are not limited to the embodimentsdescribed above, and various modifications are possible withoutdeparting from the scope of the present disclosure.

REFERENCE SIGNS LIST

11 IMAGING DEVICE

12 PIXEL ARRAY UNIT

13 VERTICAL DRIVING UNIT

14 COLUMN PROCESSING UNIT

15 HORIZONTAL DRIVING UNIT

16 OUTPUT UNIT

17 DRIVING CONTROL UNIT

21 PIXEL

22 HORIZONTAL SIGNAL LINE

23 VERTICAL SIGNAL LINE

24 PD

25 TRANSFER TRANSISTOR

26 FD

27 AMPLIFICATION TRANSISTOR

28 SELECTION TRANSISTOR

29 RESET TRANSISTOR

31 ON-CHIP LENS

32 COLOR FILTER

33 LIGHT RECEIVING LAYER

34 MULTILAYER WIRING LAYER

35 SUPPORTING SUBSTRATE

41 SEMICONDUCTOR SUBSTRATE

42 TRENCH

43 CHARGE FILM

44 INSULATING FILM

45 PLANARIZING FILM

46 LIGHT SHIELDING PORTION

47 INSULATING FILM

48 GATE ELECTRODE

49 CONCAVE PORTION

What is claimed is:
 1. An imaging device, comprising: a semiconductorsubstrate having a light receiving side; a plurality of photoelectricconversion units in the semiconductor substrate; a trench regiondisposed between adjacent photoelectric conversion units; an insulatingfilm disposed at the light receiving side of the semiconductorsubstrate; and a metallic portion formed into a substantially V-shapeprotruding into the semiconductor substrate at a location correspondingto the trench region, wherein the insulating film is further disposed inthe trench region, and wherein the metallic portion includes at leastone metallic element.